Genetic analysis of the brahma gene of Drosophila melanogaster and polytene chromosome subdivisions 72AB.

Abstract The brahma gene is required for activation of the homeotic genes of the Antennapedia and bithorax complexes in Drosophila. We have isolated and characterized 21 mutations in brahma. We show that both maternal and zygotic functions of brahma are required during embryogenesis. In addition, the severe abnormalities caused by loss of maternal brahma expression show that the homeotic genes are not the only targets for brahma activation. The complex pattern of interallelic complementation for the 21 brahma alleles suggests that brahama may act as a multimer. In addition to mutations in brahma, we have isolated mutations in four other essential genes within polytene chromosome subdivisions 72AB. Based on a compilation of similar studies that include about 24% of the genome, we estimate that about 3600 genes in Drosophila can mutate to cause recessive lethality, with fewer than 900 additional genes essential only for gametogenesis. We have identified three times more transcripts than lethal complementation groups in 72AB. One transcript in 72AB is the product of the essential arf-like gene and encodes a member of the ARF subfamily of small GTP-binding proteins. Two other transcripts are probably the products of a single gene whose protein products are similar to the catalytic subunits of cAMP-dependent protein kinases.

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Genetic Analysis of Delta, a Neurogenic Gene of Drosophila melanogaster

Genetics ◽

10.1093/genetics/116.3.433 ◽

1987 ◽

Vol 116 (3) ◽

pp. 433-445

Author(s):

Harald Vässin ◽

Jose A Campos-Ortega

Keyword(s):

Drosophila Melanogaster ◽

Genetic Analysis ◽

Phenotypic Expression ◽

Wild Type Allele ◽

Wild Type ◽

Type Allele ◽

Embryonic Lethal ◽

Complementation Groups ◽

Interallelic Complementation ◽

Hypomorphic Alleles

ABSTRACT We report here the results of a genetic analysis of the gene Delta (Dl) of Drosophila melanogaster. Dl has been mapped to the band 92A2, on the basis of two pieces of evidence: (1) this band is the common breakpoint of several chromosomal aberrations associated with Dl mutations and (2) recombination mapping of alleles of five different lethal complementation groups that are uncovered by Df(3R)DlFX3 (breakpoints at 91F11; 92A3). Dl was found to map most distally of all five complementation groups. The analysis of a large number of Dl alleles demonstrates the considerable genetic and functional complexity of Dl. Three types of Dl alleles are distinguishable. Most alleles behave as amorphic or hypomorphic recessive embryonic lethal alleles, which in addition cause various defects in heterozygosity over the wild-type allele. The defects are due to haplo-insufficient expression of the locus and can be suppressed by a duplication of the wild-type allele. The second class is comprised of three alleles with antimorphic expression. The phenotype of these alleles can only be reduced, rather than suppressed, by a duplication of the wild-type allele. The third group is comprised of three visible, predominantly hypomorphic alleles with an antimorphic component of phenotypic expression. The pattern of interallelic complementation is complex. On the one hand, there is a group of hypomorphic, fully penetrant embryonic lethal alleles which complement each other. On the other hand, most alleles, including all amorphic alleles, are viable over the visible ones; alleles of antimorphic expression, however, are lethal over visible alleles. These results are compatible with a rather complex genetic organization of the Dl locus.

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Genetic Analysis of the Heterochromatin of Chromosome 3 in Drosophila Melanogaster. II. Vital Loci Identified through Ems Mutagenesis.

Genetics ◽

10.1093/genetics/120.2.519 ◽

1988 ◽

Vol 120 (2) ◽

pp. 519-532

Author(s):

G E Marchant ◽

D G Holm

Keyword(s):

Drosophila Melanogaster ◽

Genetic Analysis ◽

Single Copy ◽

Chromosome 3 ◽

Temperature Sensitive ◽

Chromosome 2 ◽

Complementation Groups ◽

Sensitive Allele ◽

Interallelic Complementation ◽

The Right

Abstract Chromosome 3 of Drosophila melanogaster contains the last major blocks of heterochromatin in this species to be genetically analyzed. Deficiencies of heterochromatin generated through the detachment of compound-3 chromosomes revealed the presence of vital loci in the heterochromatin of chromosome 3, but an extensive complementation analysis with various combinations of lethal and nonlethal detachment products gave no evidence of tandemly repeated vital genes in this region. These findings indicate that the heterochromatin of chromosome 3 is genetically similar to that of chromosome 2. A more thorough genetic analysis of the heterochromatic regions has been carried out using the chemical mutagen ethyl methanesulfonate (EMS). Seventy-five EMS-induced lethals allelic to loci uncovered by detachment-product deficiencies were recovered and tested for complementation. In total, 12 complementation groups were identified, ten in the heterochromatin to the left of the centromere and two to the right. All but two complementation groups in the left heterochromatic block could be identified as separate loci through deficiency mapping. The interallelic complementation observed between some EMS-induced lethals, as well as the recovery of a temperature-sensitive allele for each of the two loci, provided further evidence that single-copy, transcribed vital genes reside in the heterochromatin of chromosome 3. Cytological analysis of three detachment-product deficiencies provided evidence that at least some of the genes uncovered in this study are located in the most distal segments of the heterochromatin in both arms. This study provides a detailed genetic analysis of chromosome 3 heterochromatin and offers further information on the genetic nature and heterogeneity of Drosophila heterochromatin.

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CYTOGENETIC ANALYSIS OF THE CHROMOSOMAL REGION IMMEDIATELY ADJACENT TO THE ROSY LOCUS IN DROSOPHILA MELANOGASTER

Genetics ◽

10.1093/genetics/95.1.95 ◽

1980 ◽

Vol 95 (1) ◽

pp. 95-110 ◽

Cited By ~ 3

Author(s):

Arthur J Hilliker ◽

Stephen H Clark ◽

Arthur Chovnick ◽

William M Gelbart

Keyword(s):

Drosophila Melanogaster ◽

Polytene Chromosome ◽

Structural Information ◽

Genetic Regulation ◽

Chromosome Band ◽

Genetic Dissection ◽

Genetic Unit ◽

Complementation Groups ◽

The Relationship ◽

Chromosome Bands

ABSTRACT This report describes the genetic analysis of a region of the third chromosome of Drosophila melanogaster extending from 87D2-4 to 87E12-F1, an interval of 23 or 24 polytene chromosome bands. This region includes the rosy (ry, 3-52.0) locus, carrying the structural information for xanthine dehydrogenase (XDH). We have, in recent years, focused attention on the genetic regulation of the rosy locus and, therefore, wished to ascertain in detail the immediate genetic environmcnt of this locus. Specifically, we question if rosy is a solitary genetic unit or part of a larger complex genetic unit encompassing adjacent genes. Our data also provide opportunity to examine further the relationship between euchromatic gene distrihution and polytene chromosome structure.—The results of our genetic dissection of the rosy microregion substantiate the conclusion drawn earlier (SCHALET, KERNAGHAN and CHOVNICK 1964) that the rosy locus is the only gene in this region concerned with XDH activity and that all adjacent genetic units are functionally, as well as spatially, distinct Erom the rosy gene. Within the rosy micro-region, we observed a close correspondence between the number of complementation groups (21) and the number of polytene chromosome bands (23 or 24). Consideration of this latter observation in conjunction with those of similar studies of other chhromosomal regions supports the hypothesis that each polytene chromosome band corresponds to a single genetic unit.

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GENETIC ANALYSIS OF THE ANTENNAPEDIA GENE COMPLEX (ANT-C) AND ADJACENT CHROMOSOMAL REGIONS OF DROSOPHILA MELANOGASTER. II. POLYTENE CHROMOSOME SEGMENTS 84A–84B1,2

Genetics ◽

10.1093/genetics/95.2.383 ◽

1980 ◽

Vol 95 (2) ◽

pp. 383-397

Author(s):

R A Lewis ◽

B T Wakimoto ◽

R E Denell ◽

T C Kaufman

Keyword(s):

Drosophila Melanogaster ◽

Genetic Analysis ◽

Normal Development ◽

Chromosome 3 ◽

Gene Complex ◽

Functional Sites ◽

Complementation Groups ◽

Chromosome Segments ◽

New Alleles ◽

New Mutations

ABSTRACT The existence of a gene complex in the proximal right arm of chromosome 3 of Drosophila melanogaster involved in the development of the head and thorax was originally suggested by the phenotypes of several dominant homoeotic mutations and their revertants. A screen for mutations utilizing Df(3R) AntpNS+R17 (proximally broken in salivary region 84B1,2) yielded, among 102 recovered mutations, 17 localized by deficiency mapping to the putative homoeotic cluster. These fell into four complementation groups, two of which were characterized by homoeotic phenotypes. To explore the limits of the Antennapedia gene complex (ANT-C) more proximally, a second screen has been undertaken utilizing Df(3R)Scr, a deficiency of 84A1-B1,2.——Of 2832 chromosomes screened, 21 bearing alterations localized to polytene interval 84A-84B1,2 have been recovered. Sixteen are recessive lethals, and five showing reduced viability display a visible phenotype in surviving individuals. Complementation and phenotypic analyses revealed four complementation groups proximal to those identified in the previous screen, including two new alleles of the recessive homoeotic mutation, proboscipedia (pb). Ten of the new mutations correspond to complementation groups defined previously in the Df(3R)AntpNS+R17 screen, four to the EbR11 group, two to the Scr group and four to the Antp group.——On the basis of the phenotypes of the 39 mutations localized to this region, plus their interactions with extant homoeotic mutations, we postulate that there are at least five functional sites comprising the ANT-C. Three have been demonstrated to he homoeotic in nature. The specific homoeotic transformations thus far observed suggest that these loci are critical for normal development of adult labial, maxillary and thoracic structures.

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A genetic analysis of the rudimentary locus of Drosophila melanogaster

Genetics Research ◽

10.1017/s0016672300012039 ◽

1971 ◽

Vol 17 (1) ◽

pp. 53-81 ◽

Cited By ~ 62

Author(s):

Peter S. Carlson

Keyword(s):

Drosophila Melanogaster ◽

Fine Structure ◽

Functional Organization ◽

Complex Pattern ◽

Intragenic Recombination ◽

Interaction Data ◽

Complementation Groups ◽

Interallelic Complementation ◽

Genetic Fine Structure ◽

Fungal Genes

SUMMARYA study of the structural and functional organization of the rudimentary (r: 1–54·5) locus of Drosophila melanogaster has demonstrated that alleles of this gene reside in a number of recombinationally separable sites, and display a complex pattern of interallelic interaction. Data relating to interallelic interaction have been utilized to construct a linear complementation map consisting of 7 complementation units and 16 complementation groups. Comparison of the genetic fine structure map and the complementation map shows that the two maps are approximately co-linear. Totally non-complementing alleles reside at both ends of the fine structure map. The r locus is best interpreted by the model of a single cistron whose product affects several distinct developmental processes and whose alleles display a complex pattern of interallelic complementation. Intragenic recombination within the r locus is accompanied by the appearance of parental and recombinant flanking marker classes not expected on the basis of reciprocal recombination. Studies with half-tetrads demonstrate that intragenic recombination can occur either by gene conversion or by a reciprocal exchange mechanism. The pattern of organization seen at the r locus is similar to patterns of organization found in work with fungal genes.

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Genetic analysis of the adenosine3 (Gart) region of the second chromosome of Drosophila melanogaster.

Genetics ◽

10.1093/genetics/124.4.889 ◽

1990 ◽

Vol 124 (4) ◽

pp. 889-897

Author(s):

S Y Tiong ◽

D Nash

Keyword(s):

Drosophila Melanogaster ◽

Genetic Analysis ◽

Gene Product ◽

Genetic Interaction ◽

Chromosome Region ◽

The Other ◽

Purine Biosynthesis ◽

Induced Mutations ◽

Complementation Groups ◽

Functional Complexity

Abstract The Gart gene of Drosophila melanogaster is known, from molecular biological evidence, to encode a polypeptide that serves three enzymatic functions in purine biosynthesis. It is located in polytene chromosome region 27D. One mutation in the gene (ade3(1)) has been described previously. We report here forty new ethyl methanesulfonate-induced mutations selected aga!nst a synthetic deficiency of the region from 27C2-9 to ++28B3-4. The mutations were characterized cytogenetically and by complementation analysis. The analysis apparently identifies 12 simple complementation groups. In addition, two segments of the chromosome exhibit complex complementation behavior. The first, the 28A region, gave three recessive lethals and also contains three known visible mutants, spade (spd), Sternopleural (Sp) and wingless (wg); a complex pattern of genetic interaction in the region incorporates both the new and the previously known mutants. The second region is at 27D, where seven extreme semilethal mutations give a complex complementation pattern that also incorporates ade3(1). Since ade3(1) is defective in one of the enzymatic functions encoded in the Gart gene, we assume the other seven also affect the gene. The complexity of the complementation pattern presumably reflects the functional complexity of the gene product. The phenotypic effects of the mutants at 27D are very similar to those described for ade2 mutations, which also interrupt purine biosynthesis.

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Genetic and molecular mapping of chromosome region 85A in Drosophila melanogaster.

Genetics ◽

10.1093/genetics/120.3.733 ◽

1988 ◽

Vol 120 (3) ◽

pp. 733-742

Author(s):

W K Jones ◽

J M Rawls

Keyword(s):

Drosophila Melanogaster ◽

Genetic Analysis ◽

Molecular Mapping ◽

Chromosome Region ◽

Chromosome Rearrangements ◽

Genetic Complementation ◽

Chromosomal Segment ◽

Molecular Map ◽

Molecular Studies ◽

Complementation Groups

Abstract Chromosome region 85A contains at least 12 genetic complementation groups, including the genes dhod, pink and hunchback. In order to better understand the organization of this chromosomal segment and to permit molecular studies of these genes, we have carried out a genetic analysis coupled with a chromosome walk to isolate the DNA containing these genes. Complementation tests with chromosomal deficiencies permitted unambiguous ordering of most of the complementation groups identified within the 85A region. Recombinant bacteriophage clones were isolated that collectively span over 120 kb of 85A DNA and these were used to produce a molecular map of the region. The breakpoint sites of a number of 85A chromosome rearrangements were localized on the molecular map, thereby delimiting regions of the DNA that contain the various genetic complementation groups.

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HYPOMORPHIC LETHAL MUTATIONS AND THEIR IMPLICATIONS FOR THE INTERPRETATION OF LETHAL COMPLEMENTATION STUDIES IN DROSOPHILA

Genetics ◽

10.1093/genetics/105.4.957 ◽

1983 ◽

Vol 105 (4) ◽

pp. 957-968

Author(s):

David Nash ◽

Frank C Janca

Keyword(s):

Drosophila Melanogaster ◽

X Chromosome ◽

Small Region ◽

Essential Genes ◽

Activity Levels ◽

Lethal Mutations ◽

Homozygous Mutant ◽

Complementation Groups ◽

Interallelic Complementation ◽

Hypomorphic Alleles

ABSTRACT In a small region of the X chromosome of Drosophila melanogaster, we have found that a third of the mutations that appear to act as lethals in segmental haploids are viable in homozygous mutant individuals. These viable mutations fall into four complementation groups. The most reasonable explanation of these mutations is that they are a subset of functionally hypomorphic alleles of essential genes: hypomorphic mutations with activity levels above a threshold required for survival, but below twice that level, should behave in this manner. We refer to these mutations as "haplo-specific lethal mutations." In studies of autosomal lethals, haplo-specific lethal mutations can be included in lethal complementation tests without being identified as such. Accidental inclusion of disguised haplo-specific lethals in autosomal complementation tests will generate spurious examples of interallelic complementation.

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Cytogenetic definition and morphogenetic analysis of Delta, a gene affecting neurogenesis in Drosophila melanogaster.

Genetics ◽

10.1093/genetics/118.2.235 ◽

1988 ◽

Vol 118 (2) ◽

pp. 235-245

Author(s):

A K Alton ◽

K Fechtel ◽

A L Terry ◽

S B Meikle ◽

M A Muskavitch

Keyword(s):

Nervous System ◽

Drosophila Melanogaster ◽

Genetic Analysis ◽

Inverse Correlation ◽

Small Interval ◽

Genetic Analyses ◽

The Third ◽

Complementation Groups ◽

Definition Of ◽

Morphogenetic Analysis

Abstract We have conducted a genetic analysis of a small interval of the third chromosome known to include Delta (Dl), a locus that affects the segregation of the ectoderm into neural and epidermal lineages during embryogenesis and the morphogenesis of some ectodermally derived structures, in Drosophila melanogaster. This analysis has led to the definition of seven independent complementation groups, one of which is Delta, within the interval extending from 91F6-13 to 92A2. Among the extant mutations in these seven loci, only mutations in Dl lead to the so-called neurogenic phenotype: hypertrophy of the nervous system and reduction of the epidermis. Combined cytogenetic and genetic analyses allow us to define absolute proximal (91F5-92A1) and distal (92A2) cytogenetic limits for the Dl locus. We have isolated hypomorphic and amorphic alleles of Dl and find that, for any given allele, there is an inverse correlation between neural hypertrophy and epidermal reduction in embryos and a direct correlation between the severity of embryonic phenotypes in mutant homozygotes and hemizygotes and the imaginal phenotype in heterozygous adults.

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Genetic analysis of enhancer of split, a locus involved in neurogenesis in Drosophila melanogaster.

Genetics ◽

10.1093/genetics/119.1.63 ◽

1988 ◽

Vol 119 (1) ◽

pp. 63-74

Author(s):

A Ziemer ◽

K Tietze ◽

E Knust ◽

J A Campos-Ortega

Keyword(s):

Drosophila Melanogaster ◽

Genetic Analysis ◽

Spontaneous Mutations ◽

Genetic Complexity ◽

Complementation Groups ◽

Enhancer Of Split

Abstract Enhancer of split (E(spl)), one of the neurogenic loci of Drosophila, is uncovered by the deletion Df(3R)E(spl)(R-B251) with breakpoints at 96F8 and 96F13. We describe here the results of a genetic analysis of this chromosomal interval. Thirty-one mutations in genes of this region were recovered during various programs of mutagenesis. In addition, we included the spontaneous mutations E(spl)(D) and groucho (gro), which are known to map to this region, in our study. These 33 mutations define four lethal complementation groups, one of which includes E(spl)(D) and gro. Mutations of the E(spl) group behave as complementing and noncomplementing pseudoalleles, defining different functions. Alleles are classified according to their complementation behavior in two different ways: with respect to their viability as heterozygotes with other lethal alleles and with respect to gro and to E(spl)(D). The phenotypes of these mutations and the pattern of heteroallelic complementation speak in favor of a considerable genetic complexity of the E(spl) locus.

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